add rle v2 encoding for segment v2

[kangpinghuang]

1. reuse the rle encoding in alpha rowset
2. modify segment_test because of change of encoding

issue: #2886

[chaoyli]

If you just move the old code from the AlphaRowset, the question of AlphaRowset still exists.
Like

• I/O exemplification of read StreamHead.

• Two much virtual functions of read caused by streaming read of ORC.

• Not import ORCFile the latest enhancement in recent years.

This are all questions we start to build SegmentV2.